A method of and an apparatus for welding such an edge bar to the ends of the support bars and filling bars of a bar grate are described in Federal Republic of Germany-Auslegeschrift No. 15 65 688. The procedure of this known method is substantially that an edge bar is brought up to a bar grate, anchored stationarily upon the welding bench and is then welded to the bar grate. In this case it is necessary to turn the bar grate four times so as to introduce the necessary edge bar on all four sides. The known method, which is still practiced on a large scale nowadays, is relatively extravagant of time and therefore of cost.